Identify the given values (moles and/or volume, and whether volume is in L or mL)
If you have moles and volume: use ( M = dfrac{n}{V} )
If volume is in mL: convert to liters ( (V_{text{L}} = dfrac{V_{text{mL}}}{1000}) )
If you have mass of solute: find moles first using ( n = dfrac{m}{M_r} )
Then calculate molarity using ( M = dfrac{n}{V} )
If you have grams and molar mass in g/mol: use ( n = dfrac{m (text{g})}{M_r (text{g/mol})} )
If you have a solution with known mass percent and density: compute solute mass from percent, then moles, then divide by total solution volume
If you have dilution information: use ( M_1V_1 = M_2V_2 )
Report units as ( text{mol/L} )